Diagnostic significance of ilioinguinal nodal uptake percentages in lower limb lymphoscintigraphy

PURPOSE: This study investigated the significance of ilioinguinal nodal uptake percentages in the evaluation of lower limb lymphoscintigraphy. METHODS: Lymphoscintigraphy studies from 161 patients were retrospectively evaluated. Region-of-interest counts from the injection sites at baseline and from whole-body images at 120 min were corrected for count duration and radioactive decay; ilioinguinal nodal uptake percentages were then calculated for each lower limb. Nodal uptake percentages were compared between normal and abnormal findings in the corresponding limbs and among the study-specific lymphoscintigraphic classification groups. RESULTS: The median ilioinguinal nodal uptake was 18.6%, with an interquartile range of 11-27, in 127 limbs with a normal lymphoscintigraphic pattern. Uptake values were higher in limbs showing features suggestive of increased lymphatic flow reserve, such as collateral lymphatic channels, but decreased with progressive lymphatic dysfunction (P < 0.001). Uptake values differed significantly among the study-specific lymphoscintigraphic classification groups (P < 0.001). Visual assessments showed a moderate correlation with semiquantitative assessments in determining asymmetry of the ilioinguinal lymph nodes on both sides (Pearson's r = 0.52, P < 0.001). CONCLUSION: Although ilioinguinal nodal uptake percentages are widely distributed, the observed distribution in limbs with normal lymphoscintigraphic patterns and selected threshold values may support visual interpretation.